Class: TEgFireGrid
function EffectiveColumns: TEgFireGridColumns;Returns the columns the grid is using: Columns when it
holds any column, otherwise the default columns the grid builds from the
dataset’s fields. Hidden columns are included; VisibleColumns
leaves them out.
Code that must work with or without explicit columns (the column
helpers, a loop over the columns to save their widths) uses
EffectiveColumns. The default columns are rebuilt whenever
the dataset’s fields change, so a reference to one of them must not be
kept.